This invention relates to sound-insulating mounts for internal combustion engines and, more particularly, to such mounts containing elastomeric material and having a stop limiting the deformation of the elastomeric material.
Heretofore, sound-insulating mounts of the foregoing type, which provide a substantially S-shaped characteristic curve of spring displacement plotted against load, have been described, for example, in German Pat. No. 3,506,977. As described in that patent, an engine mount having good insulation against conducted sound is provided despite deformation of an elastomeric pad by pre-stress and under dynamic load by providing an elastomeric material having transverse passages or cavities serving to convert acoustic energy into heat. In the mounts described therein, pan-shaped support elements embrace the elastomeric pad with sufficient clearance so as not to impede its deformation during dynamic operation. To provide a deformation-limiting stop, a peripheral region of one of the elements has a more or less C-shaped cross-section which embraces a marginal projection of the other element. The C-shaped peripheral region includes an elastic liner which is spaced from the marginal projection of the other element. When certain amplitudes of element displacement occur in the operation of the internal combustion engine for a motor vehicle, the elastic liner comes into contact with the marginal projection so that an elastic stop is provided.
An additional prior art reference is U.S. Pat. No. 1,729,394, which describes a mount for an internal combustion engine having a compressible pad of more complicated structure. In this case, the mount includes several components which are combined by a central bolt into a subassembly supplied in combination with an engine bracket and then riveted to a frame member in the vehicle. No pre-stress of the compressible pad is contemplated in that mount and the static load, i.e., the weight of the engine, is taken up by a spring which supports the bolt. In addition, this known design has no stop providing any elastic limitation of the compressible pad displacement.